The present invention relates to an electrical connector for flat multiconductor cable. More particularly the present invention relates to a flat cable electrical connector having at least three rows of connection contacts mounted at a defined distance from one another in an elongate body of insulating material, with the contacts comprising sockets or pins which extend toward one, outer surface of the insulating body and which are each connected, by way of a respective center connecting section, with a respective conductor terminal of the insulation piercing or displacement type (IDC) which each have the shape of a pair of contact fingers extending approximately mutually parallel toward the opposite outer surface of the insulating body, and with the conductor terminals being longitudinally spaced differently from one another than the respective connection contacts and being located such that each conductor of the flat cable can be pressed between a respective pair of contact fingers and contacted by piercing the insulation surrounding the conductor.
A known 50-pole flat cable connector of the above described type, a so-called D-subminiature connector is disclosed in DE-OS No. 3,151,563 corresponding to U.S. Pat. No. 4,437,723. In this connector, the center connecting sections of each row lead from respective connection contacts in a common plane to the associated conductor terminals arranged in a corresponding row and also located in the common plane. That is, in the known connector, three parallel planar rows of contact elements are provided with each of the two outer rows having 17 connection contacts and an associated outer row of 17 conductor terminals extending in a common plane, while the center row has 16 connection contacts and 16 conductor terminals which extend in a common plane parallel to and between the planes of the connection contacts and conductor terminals of the two outer rows. Although this D-connector structure for flat cable connections permits economical manufacture in that the three rows of contact elements, which each comprise a connection contact, a central connecting station and a conductor terminal of the insulation displacement type, can be cut out of three identically shaped strips of contact metal which have previously been attached to one surface of a respective flat insulating carrier or support, this connector has the drawback that, due to the close arrangement of the contact elements, very little contact metal strip material is available for forming the connection contacts. For example, there is not sufficient material to configure at least the socket type connection contacts in the form of tubes or sleeves. Rather, it is merely possible to form elastic tongues which are arranged next to one another like the teeth of a comb and which are each able to form a current transfer point with the associated countercontact only from one side. This type of current transfer leaves something to be desired, particularly when vibrations or shocks act on the connector. A further drawback of this known connector caused by the close arrangement of the contact elements in the connector is the danger of interfering with the dielectric material between successive adjacent contact elements resulting in breakdowns or short circuits.
It should be noted that in order to avoid the above-mentioned drawbacks of the above described prior art flat cable connector wherein the connecting elements (each including a connection contact, a center connecting section and an IDC conductor terminal) of each row are arranged on one of the two surfaces of a flat insulating carrier which supports these contact elements in the connector, it has already been proposed to bring the center connecting sections and the IDC conductor terminals out of the plane of the connection contacts by a small step and to mount them in alternating sequence on one of the two opposed outer surfaces of the flat insulating carrier. Due to this alternating arrangement, greater spaces exist between adjacent contact elements, and in particular, the center connecting sections and the conductor terminals, and therefore better dielectric action. Moreover, as a result of the manner in which the contact elements are formed, more contact metal is available for each contact element for forming the connecting contacts. Consequently, the latter need no longer be provided in the form of tongues which form a current transfer point with the countercontact only from one side. Rather, the connecting contacts can be provided with the configuration of tubular sockets or sleeves which assure proper current transfer. The above-mentioned advantages of this latter prior art embodiment, however, must be paid for by a significantly more complicated manufacturing process. In particular, the individual contact elements cannot, as in the previously known embodiment, be cut out of a single contact metal strip after it has been applied to the surface of the insulating support so that the contact elements are immediately provided in a suitable form and at the correct location. Instead, the individual contact elements must first be cut out of a sheet metal strip and then must be applied to one of the two sides of the insulating carrier.
It must further be pointed out that a flat cable connector is already known (German Patent No. 2,738,869) wherein a plurality of connection contacts are each connected with IDC conductor terminals by way of differently bent connecting arms which serve to compensate for the different distances between the connection contacts on the one hand and the conductor terminals on the other hand. This prior art flat cable connector, however, is designed to have a maximum of only two rows and its structural configuration cannot be transferred to connector devices with more than two rows.